Starting switch for electric motors



July 6, 1926.

1,591,457 G. S. LEDDICK STARTING SWITCH/FOR ELECTRIC MOTORS Filed Oct.. 8, 1924 2 Sheets-Sheet l III ' George S .I .eddic-K,

July 6 1926.

G. S. LEDDICK STARTING SWITCH FOR ELECTRIC MOTORS Filed Oct. 8, 1924 Fig-5.

2 Sheets-Sheet 2 Inventor: George SLeddc K, bBHsIl-ov'neg.

Patented July 6, 1926.

UNITED sTATEs'PATENT OFFICE..

GEORGE S. LEDDICK, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK.

STARTING SWITCH FOR ELECTRIC MOTORS.

Application led October 8, 1924. Serial No. 742,473.

Another object of my invention is to provide a simple and improved type of latching mechanism for a switch of the above type which will prevent the starting switch from being operated to its final position without first being placed in a predetermined intermediate position.

Another object of my invention is to provide a novel arrangement of a holding means Jfor a switch of the above type whereby i' said holding means is effective to hold said switch in its intermediate position as well as 11i its final position.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and Jforming a part of this specification. For a better understanding of my invention, reference may be had to the following description taken in connection with the ac coinpanying drawings, in which Fig. 1 is a plan view of a switch built in accordance with my invention and adapted for use in starting an alternating current motor; Fig. 2 is a side elevation of the switch shown in Fig. 1; the switch being shown in its tinal or ruiming position; Figs. 3 and 11 are diagrammatic views of the switch shown in Fig. 1, showing the position of the contacts when the switch is in its oi and starting positions respectively, and Fig. 5 is a schematic diagram of connections showing the switch connected to an alternating current source and adapted to start an induction motor of the squirrel cage type.

The switch illust-rated in the drawing is particularly adapted for use in starting alternating current motors.v It should be understood, however, that this general arrangement is equally applicable to the start-- ing of direct current motors. The switch is provided with starting contacts 10 and running contacts 11. These contacts 10 and l1 are mounted one upon each end of a conducting cross-arm 12 carried by a movable member 13 and are adapted to make contact with cooperating stationary contacts successively. The conducting cross-arms 12 are rigidly secured to the movable member 13 and rock with the movable member 13 as the latter is rocked by the operating handle ot the switch. In order to permit of relative movements between these contacts, since they are designed to make contact in succession, advantage is taken of a diierence in the wiping arc of the different contacts, that is, the starting contacts are arranged to make contact before the running contacts and then wipe until the running contacts make contact and wipe. The starting contacts 1() and the running contacts 11 cooperate with stationary contacts 14 and 15 respectively. The movable member 13 is adapted to be connected to a manual operating means 16 by means of a latching mechanism 19 to be hereinafter described. The movement of this manual means 16 in one direction moves the starting4 contacts 10 into engagement with the stationary contacts 14 to establish starting connections for the motor. The member 13 is also provided with an armature 17 which cooperates with an electromagnetic means 18 to move the running contacts 11 toward their respective stationary contacts 15 after the starting connections are established to thus establish running connections between the source of power and the motor. The electromagnet 18 is energized when the starting contacts 10 and the stationary contacts 14 engage each other and operates to hold the armature 17 and the start-ing contacts 10 in this position, and at the same time bias the running contacts 11 toward their cooperating stationary contacts 15. The latching mechanism 19 is interposed between the movable member 13 and the manual operating means 16, which, when the movable member 13 has been moved to the starting position, serves to prevent the running contacts 11 being moved into the motor running position as a result of the bias caused by the electromagnet 18, until a reverse movement is imparted to the manual operating means 16.

The switch shown in the drawingis provided with three cross-arms 12, each carrying a starting contact 10 and a running Contact 11. The startin contacts 10 are adapted to move toward t e panel when engaging the stationary contacts 14 and the running contacts 11 are adapted to move away from the panel when engaging the stationary contacts 15, the stationary lcontacts 15 being mounted upon the panel so as to overhang the contacts 1l. The armature or holding means 17 mounted' upon the movable member 13 is yieldingly connected thereto by a spring 20. This arrangement makes it possible for the armature 17 to seal against the electromagnet 18 before the running contacts 11 have moved to the running. position.4 It should be understood, however, that the spring 20 can be dispensed with, in which case the armature 17 would be rigidlv secured tn the movable member 13 and prevented from sealing against the electromagnet 18 by the latching mechanism 19. The magnetic attraction exerted by the electromagnet 18 upon the armature 17 would then be utilized to' cause the bias of the switch toward the running position.

Referring now to the latching mechanism 19, the movable member 13 in addition to carrying the cross-arm 12 with the contacts 10, 11 and the armature 17, also carries a disc shaped member 21 which is concentric and rigidly secured thereto. The disc 21 is-located at and is secured to the end of the movable member 13 and moves adjacent a somewhat similar disc shaped member 22 which is secured to the' manual operating means 16. The discs 21 and 22 are each provided with a plurality of notches which cooperate with suitable means, to be described hereinafter, to affect the pro er sequence of operation of the starting anrunning contacts 10 and 11 respectively when the manual means 16 is operated. The disc 21 on the movable member 13 has three notches 23, 24 and 25 and the disc 22 on the operating means 16 has similar notches 26, 27 and 28. L These notches are of greater circumferential length than depth yand thus permit relative movement between the discs when in operation. The first two notches on each disc are similarly located and coincide with each other when the third notches are displaced from eachother and vice versa. A stud 29 extends outwardly from the armature 17 and engages the notches 23 and 26 of the discs 21 and 22 and a llat pawl 30 engages the notches 24 and 27 of the above discs. The pawl 30 is pivoted together with a trigger 31 to a member 32 and is provided with a spring 33 which biases the pawl 30 and the trigger 31 toward each other so that when the pawl `is raised by the disc.21 the trigger 31 will engage notch 25,4 on the disc 21 and cause it to stop, thus holding the contacts 10 and 11 in the starting position. A stud 34 projects from trigger 3l through a hole in the pawl 30 and serves as a support for the spring 33. The pawl 30 when in its lowermost position rests upon-a stud 35 projecting from the member 32 and in this position it is out of contact with the disc 21. The trigger 31 is provided with a hole through which the stud 35 projects, the stud 35 in this position serving as a guide for the trigger 31.

In Fig. 5 of the drawing, an induction motor 36 is shown adapted to be connected to an alternating current source of power 37. When the switch is moved to the starting position the holding coil 18 is energized and the motor is connected to the source of power 37 through a set of resistance elements 38 .which serve to limit' the current which willow from the lines 37 while the motor 36 is starting. When the switch is moved to the running position, the resistances 38 are short-circuited by the conducting cross arms l2 and the motor 36 is then connected directly to the source of power 37. The electromagnet 18 is shown having a circuit-interrupting switch in its energizing circuit. In this particular case the switch is illustrated as a normali closed push button 39. When it is desire to stop the motor the operator merely pushes this button and opens the electromagnet circuit. This deenergizes the holding means and permits the switch to open. It should be understood, however, that this feature canl be accomplished in many other `ways and that it forms no part of my present invention.

The operation of my switch is as follows:

Assume. that the switch is to be used in starting a motor in accordance with the arrangement illustrated in Fig. 5 of the drawing and that the switch is in the osition shown in Fig. 3 of the drawing. rIhe operator lirst moves the handle connected to the operating means 16 upwardly and thus causes the disc 22 fastened thereto to move in a clockwise direction. When the notch 26 in disc 22 engages the stud 29 on the armature 17 further movement of the operating handle will cause the stud 29 to engage notch 23 in disc 21 and thereby move this disc together with the movable member 13 and cause the armature 17 to approach the electromagnet 18 and the contacts 10 to make contact with their cooperating stationary contacts 14. As the disc 22 thus moves around, the notch 28 therein will come adjacent the trigger 31 and permit the latter to vdrop inwardly and engage the notch 25 of the disc 21, thus preventing it from going any further. This takes place before the running contacts 11 make contact with the stationary contacts 15. In other words, movement of the switch into the starting position actuates the l'atching mechanism and prevents the switch being moved into the running position as a result of this movement. At the instant the starting contacts 1() and 14 engage each other the armature 17 will be some distance from the eleetromagnet 18 but the closing of these contacts energizes the electromagnet 18, causing the armature 17 to move further and seal against the electromagnet 18. This further movementof the armature 17 will compress the spring 20, heretofore referred to, and will thereby set up a bias on the movable member 13 which will move the running contacts 11 and 15 into engagement as soon as the latching mechanism 19 is released due to a reverse movement of the operating handle. The electromagnet 18 will, however, maintain the switch in the starting position until this reverse movement is imparted to the operating handle.

When the switch is operated to the starting position by the manual means 16, the spring 33 willv be compressed by the pawl 30 and as a result will exert a force tending to rotate the disc 22 and the operating means 16 in a direct-ion opposite to that in which it was moved by the operator, and should the operator release his hold upon the starting handle after placing the switch contacts 10 in the starting position, the spring 33 will cause the disc 22 to rotate `in the opposite direction, release the trigger 31 and permit the spring 20 on the holding means 17 to move the contacts 11 into the running position thus completing the motor starting operation. In other words, the operator can either release his hold on the handle as stated above or move it in the reverse direction manually. As the operating handle is moved in the reverse direction the disc 22 will be rotated in a counterclockwise direction and as a result the notch` 28 of the disc 22 lWill be moved with respect to the trigger 31 so as to force it out of the notch 25 of the disc 21.' As soon as the trigger 31 disengages notch 25 of the disc 21 the spring 20 will eX- pand and cause the movable member 13 to rotate through a further are suiiicient to cause the contacts 11 to engage their cooperating stationary contacts 15.

An important feature of the above invention, which will be evident from the above- -description and the drawings, is that movement of the operating handle in the direction to move either the Starting contacts or the running contacts toward their closing positions Awill result in both of these sets of contacts moving in the same direction and since the starting contacts 10 are arranged to make contact with the stationary contacts 14. before the running contacts 11 make contact with the stationary contacts 15, it will be impossible for the switch to be moved inte the running position without being irst placed in the starting position.

When the ystarting contacts 10 engage the stationary contacts 14.-,\the current Will low from the lines 37 through the contacts 10 and 11 and a suitable flexible conductor which is secured to the cross arms 12, to the resistance r`unit 38, through the resistance unit 38 and then to the mot-or 36, and when the running contacts 11 engage their cooperating stationary contacts 15 the current will pass from the lines 37 through the contacts 10 and 14, through the cross arm 12 to contacts 11 and 15 and then directly to the motor without passing through the resistance units 38. The electromagnet 18 as shown in the drawing is energized from a single phase of the lines 37, connections being made on two of the cross arms 12.

In accordance With the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a starting switch for electric motors, the combination et' starting and running contacts mounted upon a single operating membcr, stationary contacts adapted to cooperate with said starting and running contacts, means operable in one direction for moving said operating member into its starting position, means for holding said operating member in the starting position and biasing said operating member' toward the running position when held in its starting position, and a latching mechanism adapted to hold said contacts against said bias and out of the running position after being placed in the starting position until a reverse movement is imparted to the said rst vmentioned means.

2. In a starting switch for electric motors, the combination of starting contacts mounted upon a slngle operating member, stationary contacts adapted to cooperate With said starting and running contacts, means operable in one direction for moving said operating member into its starting position and operable in the opposite direction for moving said operating member into its running position, means for holding said operating member in the starting position and biasing said operating member toward the running position when held in its starting position, and a latching mechanism adapted to hold said vcontacts against said bias and out of the running position after being placed in the starting position until a reverse movement is imparted to said .first mentioned means.

3. In a starting switch for electric motors, the combination of movable contacts having and running motor startin and motor running positions, means operabIe in one direction for moving said contacts into starting position, means for holding said contacts in said position, resilient means cooperatin with said holding means for biasing sai' contacts toward the running position, and a latching mechanism for holding said contacts out ofthe running position until a reverse movement is imparted to said iirst mentioned means.

4. In a starting switch for electric motors, the combination of movable contacts having motor startin and motor running positions, means opera le in one direction for moving said contacts into starting position and operable in the opposite direction for moving said operating member into its running position, meansifor holding said contacts in said positions, resilient means cooperating with said holdin means for biasing said contacts toward t e running position, and a latching mechanism for holding lsaid contacts out of the running position until a reverse movement is imparted to said first mentioned means.

5. In a starting switch for electric motors, the combination of movable contacts having motor starting and motor running positions, means operable in one direction for moving said contacts into starting position, means for holding said contacts in said start-in position, resilient means cooperating witlgi said holding means for biasing said contacts toward the running position, a latchin mechanism for holding-said contacts out o the running position until a reverse movement is imparted to said first mentioned means, and resilient means for releasing said latching mechanism and imparting a reverse movement to said first mentioned means when the latter is released f by the operator.

-6. In a starting` switch for electric motors, the combination of movable contacts having motor starting and motor running positions, means operable in one direction for moving said contacts into startin position and operable' in the opposite direction for moving said operating member into its running position, means for holding said contacts in said starting osition, resilient means cooperatingl with said holdin means for biasing said contacts toward t e running position, a latching mechanism for holding said contacts out of the running position until a reverse movement is imparted to said iirst mentioned means, and resilient means for releasing said latching mechanism and imparting a reverse movementto said lirst mentioned means when the latter is released by the operator.

7. In a starting switch for electric motors, the combination of a lurality of contacts adapted to be successively moved into starting and running positions, an electromagnet for biasing said contacts to move from the first to the second of the above positions, operating means movable in one direction for moving said contacts into the first of the above positions, and a latehing mechanism adapted to prevent said contacts being moved into the running position until they have first occupied the starting position and until a reverse movement is imparted to said operating means.

8. In a starting switch for electric motors, the combination of a movable shaft, a plurality of movable contacts mounted upon said shaft, stationary contacts adapted to cooperate with said movable contacts, means operable in one direction for moving a portion of said movable contacts into contact with a portion of said stationary contacts, means for holding said movable contacts in the above position, means cooperating with said holding means for biasing the remaining portion of said movable contacts toward the remaining stationary contacts, and a l'atching mechanism for holding said remaining contacts out of contact with their cooperating stationary contacts until a reverse movement is imparted to said first lmentioned means.

9. In a starting switch for electric motors, the combination of a rotatable shaft, a plurality of contacts carried by said shaft and adapted to be successively moved into starting and running positions, means for moving said shaft and said contacts into the above positions, holding means for said switch loosely mounted upon said rotatable shaft, and resilient means for connecting said holding means to said shaft and biasing said contacts toward the running posipion when said holding means is in operaion.

10. In a starting switch for electric motors, the combination of a rotatable shaft, a plurality of contacts carried by said shaft and adapted to be moved into a starting and a running position, holding means for said contacts mounted upon said shaft, resilient means for yieldingly securing said holding means to said shaft, operating means movable in two directions, a pair of cooperating members, one secured to said rotatable shaft and one secured to said operating means, an arm projecting from said holding means and engaging said members, and a latching mechanism cooperating with said members adapted to stop said rotatable shaft with said contacts in the starting position after said operating means has moved in one direction and then permit said resilient means to move said contacts into the running positions upon a reverse movement of said operating means.

11. In a starting switch for electric motors, the combination of a movable shaft, a plurality of movable contacts mounted upon said shaft, stationary contacts adapted to cooperate with said movable contacts, means operable in one direction for moving a portion of said movable contacts into contact with a portion of said stationary contacts, means for holding said movable contacts in the above position, means cooperating with said holding means for biasing the remaining portion of said movable contacts toward the remaining stationary contacts, and a latching mechanism for holding said 'remaining contacts out of contact with their cooperating statlonary contacts until a reverse movement is imparted to' said first mentioned means, said first mentioned contacts remaining in contact after said last mentioned contacts make contact with their respective cooperating contacts.

12. In a starting switchfor electric motors, the combination of a rotatable shaft, a plurality .of oppositely disposed contacts carried by said shaft andadapted to be successively moved into starting and running positions, means for moving said shaft and lsaid contacts into the above positions, an electromagnetic holding means for said switch loosely mounted upon said rotatable shaft, and resilient means for connecting said electroma etic holding means to said shaft and biaslng said contacts toward the running position when said electromagnetic means is energized.

13. In a starting switch for electric motors, the combination of a rotatable shaft, a plurality of contacts carried by said sha-ft and adapted to be moved into a starting and a running position, electromagnetic holding means for said contacts loosely mounted `upon said shaft, resilient means for yieldingly securing said holding means to said shaft and biasing said contacts toward the running position when said electromagnetic means is energized, movable means operable in two directions, a pair of cooperating discs one secured to said rotatable shaft and one secured to said movable means, and an arm projecting from said electromagnetic means and engaging said discs, a latching mechanism cooperating with said discs adapted to stop said movable means in the starting position after said means has operated in one direction and then permit said resilient means to move said contacts into the running position upon a reverse movement of said movable means. l 14. In a control system for electric motors, the combination of a starting switch having movable contacts adapted to be moved into motor starting and motor running positions, means operable in onel direction for moving said contacts into starting position, electromagnetic means for holding said contacts in either of said positions, resilient means cooperating with said electromagnetic `means for biasing said contacts when in starting position to the running position, a latching mechanism for holding said contacts out of the running position until a reverse movement is imparted to said rst mentioned means, and connections whereby the motor is first connected to a source of power through a resistance and then directly connected to the source of power as said first mentioned means is operated.

15. In a control system for electric motors, the combination of ya starting switch having movable contacts adapted to be moved into motor starting and motor running positions, means operable in one direction for moving said contacts into starting position, electromagnetic means for lholding said contacts in either of said positions, resilient means cooperating with said electromagnetic means for biasing said contacts when in starting position to the running positions, a. latching mechanism for holding said contacts out of the running position until a reverse movement is imparted to said first mentioned means, and connections whereby' said electromagnetic means is energized and the motor is first connected to a source of power through a re- Sistance and then directly connected to the source of power as said first mentioned means is operated, said electromagnetic means being continuously energized during the above operation. u

In witness whereof I have hereunto set my hand. this 7th day of October 1924.

GEORGE S. LEDDICK. 

